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Facile synthesis of trifluoromethyl covalent organic framework for the efficient microextraction of per-and polyfluorinated alkyl substances from milk products.

Journal of chromatography. A (2020-06-09)
Xiaowei Sun, Wenhua Ji, Shenghuai Hou, Xiao Wang
ABSTRACT

Trifluoromethyl covalent organic framework (CF3-COF) is facilely synthesized at room temperature using for solid-phase microextraction (SPME). The CF3-COF coating displays an improved extraction performance for per- and polyfluorinated alkyl substances (PFASs) comparing to amorphous polymer coating, non-contained fluorine covalent organic framework coating and commercially available SPME coating. The fluorine affinity of trifluoromethyl in CF3-COF for PFASs is demonstrated using the density functional theory calculation. Following the microextraction with CF3-COF-coated fiber, the targeted PFASs are eluted with 1 mL acetonitrile and quantified by ultrahigh performance liquid chromatography tandem mass spectrometry. The low limits of detection are 0.1-0.7 pg g-1 for milk and 0.2-0.8 pg g-1 for milk powder, suggesting the outstanding sensitivity. The precision for the method ranges between 2.9 and 9.9%. The fiber-to-fiber repeatability is in the range of 4.2-9.5%. Under the optimum conditions, the relative recoveries are 91.0-110% with RSDs ≤ 10% for milk and 89.8-111% with RSDs ≤ 10% for milk powder.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Perfluorooctanoic acid, 95%
Sigma-Aldrich
Perfluoroheptanoic acid, ≥97.0%
Sigma-Aldrich
Poly(dimethylsiloxane), viscosity 1.0 cSt (25 °C)
Sigma-Aldrich
Perfluorononanoic acid, 97%
Sigma-Aldrich
Pentafluoropropionic anhydride, purum, ≥97.0% (GC)